1. Field of the Invention
The present invention relates generally to heat exchange systems and in particular relates to apparatus and methods for controlling the rate of flow and/or the rate of heat exchange for single or multiple heat exchange systems in order to reduce the overall energy demand for all of the heat exchange systems.
2. Description of the Prior Art
A conventional heating or cooling installation for a building facility typically employs at least one heat exchange system, each system having a heat exchanger, a condenser (which is also a form of heat exchanger), a working fluid circuit between the heat exchanger and the condenser, and a working fluid in the circuit. For example, in a water-based system, the heat exchanger usually compriss a cooling tower or a deep well source of cool water, the cooled water serving as the working fluid and being delivered to the condenser by a pump. In a cooling tower system, a fan is utilized to blow across the water as it trickles down the cooling tower, in order to remove heat. In the condenser, the cooled water is used to exchange heat with a conventional refrigerant (such as freon), permitting the refrigerant to then be used for cooling purposes.
There is a need for efficiently controlling both single and multiple heat exchange systems to reduce the overall energy demand.
A number of prior art arrangements deal with multiple heat exchange systems working together. For example, in U.S. Pat. No. 3,167,113, Kleiss discloses techniques for equalizing loads on multiple heat exchangers. A somewhat similar arrangement is disclosed by Funk in U.S. Pat. No. 4,381,814.
Carson, in U.S. Pat. No. 4,197,868, discloses a control system for regulating the division of a single feed stream between two or more heat exchange units operating in parallel. In U.S. Pat. No. 4,474,169, Steutermann discloses a control arrangement for multiple solar heat collecting systems. Other prior art of interest is contained in U.S. Pat. No. 3,995,443 to Iversen and U.S. Pat. No. 4,168,030 to Timmerman. Other United States patents of interest are found in Class 165, Subclasses 1, 13, 22, 31, 34, 35, 38 and 40 in the search records of the United States Patent and Trademark Office.